The 4400 tells the stories of 4,400 people who disappeared over a period of fifty years and they all reappear at the exact same time without any memory of where they've been and what happened to them. Some of them have been altered and have strange abilities, both good and bad.

The series kicks off with a ball of light sailing toward Earth, but rather than the expected catastrophic event, thousands of people emerge from the ball of light. They returnees have been missing from a few years to several decades and no one has aged a day.